Certain aspects of this disclosure relate to an image signal processing system that includes a flash controller that is configured to activate a flash device prior to the start of a target image frame by using a sensor timing signal. In one embodiment, the flash controller receives a delayed sensor timing signal and determines a flash activation start time by using the delayed sensor timing signal to identify a time corresponding to the end of the previous frame, increasing that time by a vertical blanking time, and then subtracting a first offset to compensate for delay between the sensor timing signal and the delayed sensor timing signal. Then, the flash controller subtracts a second offset to determine the flash activation time, thus ensuring that the flash is activated prior to receiving the first pixel of the target frame.
Legal claims defining the scope of protection, as filed with the USPTO.
1. A method comprising: receiving a request by an electronic device to store a target image frame of an image scene from a set of image frames operating in a preview mode, the electronic device having an image sensor; determining whether to illuminate the image scene using a flash device; acquiring a prior image frame when it is determined to illuminate the image scene using the flash device, wherein the prior image frame occurs before the target image frame; determining an updated set of image statistics based on the prior image frame; operating the electronic device in a capture mode to acquire the target frame using the updated set of image statistics; activating the flash device in response to transitioning the electronic device to the capture mode; and storing the target image frame in a memory device of the electronic device; wherein the determining to illuminate the image scene further comprises: using a first timing signal that is delayed by a first interval with respect to a sensor timing signal provided by the image sensor, wherein the first timing signal is configured to identify a first time corresponding to an end of the prior image frame; adding a second interval between the target image frame and the prior image frame to the first time to determine a second time; subtracting the first interval from the second time to determine a third time; subtracting a third interval from the third time to determine a fourth time; and activating the flash device at the fourth time.
2. The method of claim 1 , wherein acquiring the prior image frame comprises activating the flash device during the acquisition of the prior image frame.
3. The method of claim 1 , wherein the updated set of image statistics comprises auto-white balance parameters based upon the prior image frame.
4. The method of claim 1 , wherein the request to store the target image frame is received in response to actuation of an image capture input structure on the electronic device.
5. The method of claim 4 , wherein the image capture input structure comprises a physical input structure on the electronic device or a graphical input structure provided on a graphical user interface displayed on a display device of the electronic device.
6. The method of claim 1 , wherein the preview mode comprises displaying the image scene being acquired by the digital image sensor on a display device of the electronic device.
7. The method of claim 1 , wherein the updated set of image statistics comprises color correction matrices (CCM) based upon the prior image frame.
8. The method of claim 1 , wherein operating the electronic device in the capture mode to acquire the target frame comprises: acquiring a first frame with the flash device deactivated obtaining one or more color properties associated with the first frame; acquiring the target frame with the flash device activated; and applying a color palette transfer to the target frame based at least in part on the color properties.
9. A method comprising: receiving a request on an electronic device having an image signal processing sub-system to capture a target image frame from a set of image frames corresponding to an image scene being acquired by a digital image sensor; determining whether to illuminate the image scene using a flash device during acquisition of the target image frame; acquiring a first image frame and obtaining a set of color properties based on the first image frame when it is determined to illuminate the image scene during the acquisition of the target image frame, wherein the first image frame occurs before the target image frame; activating the flash device to acquire the target image frame; processing the target image frame using the set of color properties based on the first image frame; and storing the processed target image frame in a memory device of the electronic device; wherein the determining to illuminate the image scene further comprises: using a first timing signal that is delayed by a first interval with respect to a sensor timing signal provided by the digital image sensor, wherein the first timing signal is configured to identify a first time corresponding to an end of the first image frame; adding a second interval between the target image frame and the first image frame to the first time to determine a second time; subtracting the first interval from the second time to determine a third time; subtracting a third interval from the third time to determine a fourth time; and activating the flash device at the fourth time.
10. The method of claim 9 , wherein acquiring the first image frame comprises acquiring a non-illuminated first image frame.
11. The method of claim 9 , wherein processing the target frame using the set of color properties based on the first image frame comprises applying a color palette transfer operation.
12. The method of claim 11 , wherein the color palette transfer operation is applied to the target frame.
13. The method of claim 9 , wherein activating the flash device to acquire the target image frame comprises: acquiring a second image frame when the flash device is activated; processing the second image frame to obtain an updated set of image statistics based on the second image frame; and acquiring the target image frame using the updated set of image statistics.
14. The method of claim 13 , wherein the updated set of image statistics comprises auto-white balance parameters based upon the second image frame.
15. The method of claim 13 , wherein the updated set of image statistics comprises color correction matrices (CCM) based upon the second image frame.
16. The method of claim 9 , wherein acquiring the first image frame comprises receiving an input via an image capture input structure from a user of the electronic device.
17. The method of claim 16 , wherein the image capture input structure comprises a physical input structure on the electronic device or a graphical input structure provided on a graphical user interface displayed on a display device of the electronic device.
18. An image signal processing system, comprising: an image sensor interface configured to receive image data acquired from an image sensor as a plurality of image frames; a flash controller configured to control a flash device: and image signal processing logic configured to: receive a request to store a target image frame of the plurality of image frames; acquire a first image frame having one or more color properties associated with the first image frame; acquire a second image frame when the flash device is illuminated; updating a set of image statistics based on the second image frame; and acquiring the target image frame when the flash device is illuminated, wherein the target image frame is acquired using the one or more color properties and the updated set of image statistics; wherein the flash controller is configured to: use a first timing signal received by the image sensor interface that is delayed by a first interval with respect to a sensor timing signal provided by the image sensor, wherein the first timing signal is configured to identify a first time corresponding to an end of the first image frame; add a second interval between the second image frame and the first image frame to the first time to determine a second time; subtract the first interval from the second time to determine a third time. subtract a third interval from the third time to determine a fourth time; and activate the flash device at the fourth time.
19. The image signal processing system of claim 18 , wherein the first image frame immediately precedes the second image frame.
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February 3, 2014
May 17, 2016
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